This invention relates to a device for checking the size of countersinks.
The invention applies in particular to dimensional checking for machining process certification of very large parts.
A typical application of the invention is dimensional checking of countersinks made by numerically controlled machines on large panels such as, for example, aircraft wing panels and fuselage parts.
An aircraft wing panel or a part of a fuselage requires several hundred or even thousands of countersinks to accommodate the heads of the rivets used to join the wing panel to the wing ribs or to fasten a fuselage panel to the fuselage frame.
These countersinks are usually made by numerically controlled machines where a suitable tool head machines the panel as required.
Certification of machined parts is becoming more and more a requirement as part machining and final assembly are performed by different companies.
Assembly houses require certification of every part they assemble to ensure that all prior machining processes have been performed to specifications and will not invalidate the final assembly.
At present, for certification to be obtained, it is sufficient to precisely measure only some of the countersinks made, the validity of the machining process in its entirety being determined a posteriori and only on a statistical basis.
Since machining tolerances, for example in aeronautical applications, are now required to be within 5 hundredths of a millimeter, the statistical certification process is no longer accepted and measurement of every single countersink is instead required.
In prior art, checking is carried out by one or more operators with gauge in hand to measure each single countersink.
This process, besides being very slow and therefore expensive, requires the provision of scaffolding and other equipment to allow access to the part of the panel where measurements are to be performed and to enable the operator to reach each countersink to be measured.
Moreover, checking the countersinks in the manner described above is subject to human error and to the fact that the gauges used, in order to provide a reliable reading, must be positioned on the countersink with extreme precision and meticulous care.
The Applicant has found that the instruments used for measuring the countersinks, and the measuring process itself, can be improved in several respects, especially in terms of measurement time and reliability.